4 Edit Points represented by Black Squares will be visible at the 4 corners of the Rectangle.

Microsoft Word 2010 Edit Points on Rectangle
We want to totally change this shape by adding multiple arcs to it.

This means we will have to Add New Points.

Microsoft Word 2010 Edit Points Menu - Add Point
Place your cursor at the Center of the Top 2 Points. The cursor will change to a Plus Sign with a Square at its midpoint.

Right click and select Add Point from the pop up menu that appears.
Microsoft Word 2010 Rectangle Add New Point

Continue to Add points at the perceived center of 2 points, so that you'll have 9 Points on this Top Line of the Rectangle. Repeat this process to add to the Bottom Line of the Rectangle.
Microsoft Word 2010 Rectangle with Added Points

On the Top Line of the Rectangle move your cursor over the Second Point and drag downward about 1/2 Inch.
Microsoft Word 2010 Edit Points Lowered Segment

Repeat for every other point. So now some segments will be high and some low.
Microsoft Word 2010 Line with Adjusted Segments

You should be lowering a total of 4 Points on the Top Line and 4 Points on the Bottom.
Microsoft Word 2010 Rectangle with Adjusted Line Segments

Notice what was once a rectangle is no more. Now we can add curves to all points with the exception of the Corner Points.

Next we need to Rotate this shape. Select the Image and move your cursor over the Green Circle so that it changes to a Rotation Arrow.
Microsoft Word 2010 Selected Shape

While holding down your mouse button Rotate the shape to the Left until Two of the Corners touch the side of the page. Don't worry about the other Two, we will make adjustments to them.
Microsoft Word 2010 Rotated Shape

Microsoft Word 2010 Move Top Line Segment
Select the Top Right Point and drag toward the edge of the page.